A livewell is a tank found on many fishing boats that is used to keep bait and caught fish alive. They work by pumping fresh water from the surrounding body into the tank, as well as keeping the water aerated.
A rule of thumb

Rule of thumb

A rule of thumb is a principle with broad application that is not intended to be strictly accurate or reliable for every situation. It is an easily learned and easily applied procedure for approximately calculating or recalling some value, or for making some determination...

 for determining the necessitated size of a livewell is that every one inch of fish needs a gallon of water, if it is desired to keep the fish alive for a prolonged period of time.

Besides size and water circulation, two other key factors of the functionality of a livewell are maintaining proper temperature and removing metabolic waste

Metabolic waste

Metabolic wastes or excretes are substances left over from excretory processes, which cannot be used by the organism , and must therefore be excreted. This includes nitrogen compounds, water, CO2, phosphates, sulfates, insoles, medicals, food additives etc. Animals treat these compounds as excretes...

. Water temperatures should be below 75 degrees; ice can be used as a coolant

Coolant

A coolant is a fluid which flows through a device to prevent its overheating, transferring the heat produced by the device to other devices that use or dissipate it. An ideal coolant has high thermal capacity, low viscosity, is low-cost, non-toxic, and chemically inert, neither causing nor...

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Oxygen levels

It is very important to maintain adequate oxygen levels in the livewell. It should be above 5 parts per million. Electric aeration systems are often used to do this. These often work by creating a spray that increases the surface area

Surface area

Surface area is the measure of how much exposed area a solid object has, expressed in square units. Mathematical description of the surface area is considerably more involved than the definition of arc length of a curve. For polyhedra the surface area is the sum of the areas of its faces...

 of the water, or by passing it through a Venturi

Venturi effect

The Venturi effect is the reduction in fluid pressure that results when a fluid flows through a constricted section of pipe. The Venturi effect is named after Giovanni Battista Venturi , an Italian physicist.-Background:...

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